RELEASE OF THE CELLULAR PRION PROTEIN FROM CULTURED-CELLS AFTER LOSS OF ITS GLYCOINOSITOL PHOSPHOLIPID ANCHOR
RELEASE OF THE CELLULAR PRION PROTEIN FROM CULTURED-CELLS AFTER LOSS OF ITS GLYCOINOSITOL PHOSPHOLIPID ANCHOR
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DOI：
10.1093/glycob/3.4.319
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发表时间：
1993-08-01
期刊：
影响因子：
4.3
通讯作者：
PRUSINER, SB
中科院分区：
文献类型：
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作者：
BORCHELT, DR;ROGERS, M;PRUSINER, SB
唾液酸糖蛋白的分泌型被称为细胞蛋白(PrP(C))，已被鉴定为不能用选择性剪接解释的分泌型蛋白。我们报道PrP(C)的分泌形式来自于通过糖化肌醇磷脂(GPI)锚与质膜结合的前体。新生PrP(C)经磷脂酰肌醇特异性磷脂酶C(PIPLC)消化后，可阻止分泌型PrP(C)的出现。分泌的PrP(C)像PIPLC释放的PrP(C)一样被分配到Triton X-114的水相中。用氢氟酸处理后，PIPLC释放的PrP(C)的M(R)降低了2-4 kDa，去除了整个GPI锚定修饰，而分泌的PrP(C)的M(R)没有变化。PIPLC释放的PrP(C)和分泌的PrP(C)都可被抗合成的C末端多肽(对应于220-233位氨基酸(231位氨基酸是GPI结合部位)的抗血清识别。我们得出结论，GPI锚定的PrP(C)是翻译后处理，以去除大部分GPI修饰，然后进入培养基中。PrP(C)是否在C末端附近的蛋白分解后脱落仍有待确定。在正常的叙利亚仓鼠脑中，少数PrP(C)像Share PrP(C)一样被分配到Triton X-114的水相中，这提示了生理意义。
Secreted forms of the sialoglycoprotein designated cellular prion protein (PrP(C)) have been identified that cannot be explained by alternative splicing. We report that secreted forms of PrP(C) derive from precursors that are bound to the plasma membrane by glycoinositol phospholipid (GPI) anchors. Secreted PrP(C) slowly appeared in the culture medium of metabolically radiolabelled cells after incubations of 8-24 h. Digestion of nascent PrP(C) with phosphatidylinositol-specific phospholipase C (PIPLC) prevented the appearance of secreted PrP(C). Secreted PrP(C) partitioned into the aqueous phase of Triton X-114 like PIPLC-released PrP(C). While the M(r) of PIPLC-released PrP(C) was reduced 2-4 kDa after treatment with aqueous hydroflouric acid, which removes the entire GPI anchor modification, the M(r) of secreted PrP(C) was unchanged. Both PIPLC-released and secreted PrP(C) were recognized by antiserum raised against a synthetic C-terminal peptide corresponding to residues 220-233 (amino acid 231 is the site of GPI attachment). We conclude that GPI-anchored PrP(C) is post-translationally processed to remove most, if not all, of the GPI modification and then shed into culture medium. Whether PrP(C) is shed after proteolysis near the C-terminus remains to be established. A minority of PrP(C) in normal Syrian hamster brain partitioned into the aqueous phase of Triton X-114 like shed PrP(C), suggesting physiological significance.